This invention relates to a method of cleaning articles that contain an epoxy resin. In particular, it relates to a method of removing undesirable synthetic and natural resins from those articles without dissolving the epoxy resin.
In the electronics industry, circuit boards are used that are made from epoxy resins. When components are mounted on the boards, rosins used as solder fluxes contaminate the surfaces of the board. Other synthetic and natural resins are used as adhesives, and they also end up as undesirable substances on the board. In addition, the board can be contaminated by human contact and by particles and gases from the air. In order to preserve the electrical properties of the board, it is necessary to remove these contaminants without damaging the board itself. This is accomplished by cleaning the board with a solvent that readily dissolves most synthetic and natural resins, but does not dissolve or attack the epoxy resin from which the board is constructed.
Until recently, trichlorotrifluoroethane was used for this purpose because it is a good solvent for most resins but does not attack epoxy resins. However, trichlorotrifluoroethane persists in the atmosphere and has been implicated in the depletion of the ozone layer. For this reason, its use has been restricted and it may be prohibited entirely within a few years. Efforts are being made to identify other solvents with the same desirable properties but which will not affect the ozone layer.